The first contribution can, indeed, be credited to Aristotle, whose luminous formulations concerning Energeia, Action, (as excluding Motion, or Activity), we have already referred to. Here to _be_ is to _act_, and Energeia, a being’s perfect functioning and fullest self-expression in action, is not some kind of movement or process; but, on the contrary, all movement and process is only an imperfect kind of Energeia. Man, in his life here, only catches brief glimpses of such an Action; but God is not so hampered,--He is ever completely all that He can be, His Action is kept up inexhaustibly and ever generates supreme bliss; it is an unchanging, unmoving Energeia.[286]--And St. Thomas echoes this great doctrine, for all the Christian schoolmen: “A thing is declared to be perfect, in proportion as it is in act,”--as all its potentialities are expressed in action; and hence “the First Principle must be supremely in act,” “God’s Actuality is identical with His Potentiality,” “God is Pure Action (_Actus Purus_).”[287]--Yet it is doubtless the Christian Mystics who have most fully experienced, and emotionally vivified, this great truth, and who cease not, in all their more characteristic teachings, from insisting upon the ever-increasing acquisition of “Action,” the fully fruitful, peaceful functioning of the whole soul, at the expense of “activity,” the restless, sterile distraction and internecine conflict of its powers. And Heaven, for them, ever consists in an unbroken Action, devoid of all “activity,” rendering the soul, in its degree, like to that Purest Action, God, who, Himself “Life,” is, as our Lord declared, “not the God of the dead but of the living.”[288] And the second contribution can, in part, be traced back to Plato, who does not weary, in the great middle period of his writings, from insisting upon the greatness of the nobler passions, and who already apprehends a Heavenly Eros which in part conflicts with, in part transcends, the Earthly one. But here especially it is Christianity, and in particular Christian Mysticism, which have fully experienced and proclaimed that “God” is “Love,” and that the greatest of all the soul’s acts and virtues is Charity, Pure Love. And hence the Pure Act of God, and the Action of the God-like soul, are conceived not, Aristotle-like, as acts of pure intelligence alone, but as tinged through and through with a noble emotion. (3) But in three matters the Mystics, as such and as a whole, have, here especially under the predominant influence of Greek thought, remained inadequate to the great spiritual realities, as most fully revealed to us by Christianity. The three points are so closely interconnected that it will be best first to illustrate, and then to criticise them, together.